In the production of carbonaceous products such as crude oil and the like, the viscosity of the latter and the condition of the subterranean reservoir in which it is held, often demand that some form of enhancement be utilized. Among the more common forms of enhancement is the injection of steam into the substrate at a sufficient pressure to penetrate the latter and to fluidize the carbonaceous product. The injected steam also forms a pressurized barrier to drive production fluids in a particular direction toward a producing well or wells.
It is desirable in conducting such a steaming operation, to determine the quality of the steam as it enters the substrate. The latter can be at a location any depth along the borehole, or well.
The determination of steam quality is an economic expedient since the steam will be delivered to the borehole upper end from a source, in a known condition. By the time it flows through the well bore however, and is in position to enter the substrate, the quality will generally be reduced. Without an accurate determination of quality, it is difficult to estimate the amount of heat being delivered to the substrate.
In brief, an oil field steam generator normally produces "wet steam". The steam is not 100% vapor; but does contain a liquid phase. Steam quality is a measure of the mass of vapor to the total mass of the steam. It is therefore accurate to refer to the vapor phase or the liquid phase of wet steam when quality is being considered.
Generally speaking, feed water to a steam generator contains a certain amount of dissolved solids such as salt, i.e. sodium chloride. When the water is turned into wet steam the sodium chloride cannot be contained in the vapor phase, it must be carried into the liquid phase. Therefore the salt content becomes concentrated in the liquid phase.
The higher the steam quality (i.e.: more vapor phase to liquid phase), the more concentrated the salt content becomes. To measure steam quality, the sodium chloride content of a sample of the liquid phase is ratioed to the sodium chloride content of the feed water. The amount of condensation that occurs does not affect the presently disclosed tool or steam sampler. This apparatus functions to measure the amount of condensation (i.e. loss or reduction of steam quality).
The prior art has disclosed downhole steam samplers which have been successfully utilized. These are used generally for withdrawing a sample of the liquid phase of steam from a steam flow being injected into a wall. The sample, when withdrawn from the well, can be analyzed for its chloride ion count as an aid toward establishing an accurate determination of the quality of the steam as it enters the substrate.
In the present arrangment, a steam sampler is disclosed which is both durable in structure and relatively simple to operate particularly for actuating the steam flow control valves. The sampler is comprised primarily of an elongated casing which is lowered by a wire line to a particular position within a well or borehole. The sampler casing includes an inlet at the upper end for admitting a steam flow at high pressure and temperature. A discharge opening at the casing lower end directs the pressurized flow into the well and thence into the contiguous subterranean reservoir.
The steam sampler incorporates a fluid separator which permits the liquid phase content to fall by gravity into a container, reservoir or receptacle. The vaporous segment will continue downwardly and be directed from the sampler's discharge opening.
The respective flow control valves are provided with a spring biased valve actuator rod which functions to adjust the valves from open to closed positions. The actuator rod is initially pre-set for a steam treating operation with the valves open, the rod being maintained in pre-set position by a first restraining detent.
While a flow of steam is passing through the sampler casing during a desired time period, the liquid phase will accumulate in the collecting reservoir. At the end of said time period, steam flow through the sampler is terminated to permit the sampler to be drawn from the well.
Closing of the sampler's flow control valves to discontinue steam flow therethrough is accomplished through a sleeve carried on the sampler. The sleeve includes a plurality of radially displaceable arms which are held in position by a second detent.
It is therefore an object of the invention to provide a steam sampler of the type contemplated which is responsive to surface induced actuation for closing steam flow control valves.
A further object is to provide a steam sampler that functions to discontinue steam flow therethrough in response to withdrawal of the sampler from a well.
A still further object is to provide a steam sampler having a valve triggering mechanism external of the sampler casing.